Flotation reagent and process



' dithiophosphoric acid would also be weaker.

Patented Sept. 28, 1943 FLOTATION REAGENT AND PROCESS I David Walker Jayne, Jr., 01a Greenwich, Conn., assignor to American Cyanamid Company, New York,-N. Y.-, a. corporation of Maine No Drawing. Application-November .6, 1940, Serial No. 364,495 7 14 Claims. (Cl. 209-166) This invention is directedto a composition for and a method of froth flotation of ores.

More particularly the present invention relates to a new combination of flotation promoters whereby increased eiiectiveness is obtained in froth flotation operations.

entirely satisfactory as promoters. It is also an advantage thatalthough di-tolyl thiourea and dixylyl thiourea are'practically insoluble in water they are soluble to the extent of about or more in most organic dithiophosphoric acids,

, whereas the di-phenyl thiourea of the prior art It has been known in the past that certain diaryl thioureas were promoters in the froth flotation of various ores, as for example lead sulfide ores. 'Only one of these di-aryl thioureas, namely, di-phenyl thiourea (thiocarbanilide) was considered to be sufliciently effective in froth flotation operations to economically justify its use. While it was known that higher homologues of di-phenyl thiourea, such as di-tolyl thioureas and di-xylyl thiourea, had some promoter action, they are very insoluble in water and their action is extremely weak as compared with thiocarbanilids; and as a result, they have not been used extensively in flotation operations. It has also been known in the past that the efiectiveness of thiocarbanilide as a promoter could be increased by using a mixture of thiocarbanilide and an organic dithiophosphoric acid, and such a composition is disclosed and claimed in the U. S. Patent No. 2,043,192. Since the promoter action of the higher homologues of thiocarbanilide is much' weaker than thiocarbanilide, one would expect that solutions of the higher homologues in organic In accordance with the present invention, it has been discovered that di-tolyl thiourea and diis soluble only to the extent of about 6%. Thus the present invention not only provides a reagent combination which is more effective when used xylyl thiourea are more effective promoters when mixed with an organicdithiophosphoric acid than mixtures of thiocarbanilide and organic dithiophosphoric acids, in spite of the fact that they are not effective promoters as compared to thiocarbanilide when used alone. This is a result which could not have been predicted in view of the teachings of the prior art. It might have been expected that mixtures of di-tolyl thiourea. or dixylyl thiourea and organicdithiophosphoric acids would be a more effective promoter than di-xylyl thiourea or di-tolyl thioureaalonabut it is un- -obvious that such a combination would be more in equal quantities as compared to thiocarbanilide, but also permits the preparation and use of a more concentrated solution; It isa further ad-' vantage of the present invention that although many dithiophosphates are promoters, the eifectiveness thereof is very'materially increased by the addition thereto in solution of even a relatively small amount of either di-tolyl thiourea or .di-xylyl thiourea. The increased effectiveness is not merely the sum of the effectiveness of each of the compounds constituting the mixture commonly used, but the composition is superior to either of the ingredients thereof as a flotation promoter. Organic dithiophosphoric acids generally, suchas di-alkyl or di-aryl substituted di thiophosphoric acids or their alkali metal salts and the ammonium salts, may be employed in carrying out the present invention. Whil various dithiophosphates may be utilized in conjunction with di-tolyl thiourea 0r di-xylyl thiourea, it has been found that excellent results are obtained when certain aryl dithiophosphates, as for example the di-cresyl or the di-xylenyl (mixed) dithiopho'sphoric acids, are used; As pointed out heretofore these organic dithiophosphoric acid compounds are only capable of dissolving up to about 6% of di-phenyl thiourea, whereas for example di-cresyl dithiophosphoric acid will dissolve asmuch as 10% of di-tolyl thiourea or di-Xylyl thiourea.

This invention will be more fully described in conjunction with the following specific examples. It is to be understood, however, that the examples are for purposes of illustration only andthe invention is not to be limited by the details set forth therein.

Tests were carried out on two samples of lead-- silver ores.

Sample No. 1 was from a, mine near Winnemucca, Nevada, and sample No.2 was from a mine nearSilver City, Idaho.

Partial analyses of head samples of the two above ores are shown in Table I.

A GOO-gram sample of minus 20 mesh ore was placed in a laboratory size steel rod mill and diluted with tap water to a pulp density corresponding to 67% solids. Reagents were added as shown in the data of Tables III and IV giving the results of the test work. The ore was then ground for a definite period of time. Screen analyses of the ore pulps obtained during the respective grinding periods employed on each ore are shown in Table II. Ore No. 1 was given a 15-minute grind in all tests, and the ore No. 2 sample .was subjected to a 6-minute grinding period in all tests.

test procedure and the results obtained will be found in Table III. v

Oar: No. 2'

A ground charge of the ore was transferred to a laboratory-size Fagergren flotation machine and diluted with laboratory tap water to approximately 25% solids. The pulp was conditioned for 2 minutes. The air valve was then opened and the resulting concentrate was removed by skim- TABLE'III Tnsrs 0N ORE No. 1 Test conditions Reagents, lbs/ton Pointof addition g g fgg"? pH 9 NaON ZnSO4 Naioofl 2,3 53% ,53%

Grind 15 61 0. 50 1.00 15.00 0.115 Condition 2 22 8.3 0. 112 Flotation 8 22 l Cresylic acid 0.112 lb./ton used for dryreagents-Oflfifi lb./ton used for liquid reagents.

Test results Feed assay Concentrate F Tailinz Test Promoter Assay Per cent dist. Assay Per cent dist.

(variable) Al a.) Pegoaent Per gent Per cent oz. 11 w w g Per cent Ag, Per cent rim/ton Pb Pb oz./ton b Ag Pb A 22.04 I 2. 02 12. 39 135. 46 12. 29 76. 13 75. 87. 61 6.00 0. 57 23. 87 24. 75 B 21. 39 1. 97 8. 62 178.10 15.56 71. 76 68. 02 91. 38 6. 61 0.69 28. 24 31. 98 C 22. 08 1. 95 12. 94 130. 22 12. 19 76. 31 81. 03 87. 08 6.01 0. 43 23. 69' 18. 97 D 20. 86 1. 95 12. 57 126. 70 12. 49 76. 37 80. 51 87. 43 5. 64 0.43 23.63 19. 49 E 21. 79 2.00 14 22 119. 48 11. 57 77. 97 82. 85.78 5. 59 0. 41 22. 03 17. 50

A-Thiocarbanillde (alone). B-Di-Molyl thiourea (alone). C6% solution of di-plienyl thiourea in di-xylenyl (mixed) dltlilopbosphorlc acid.

D-6% solution of di-o-tolyl thiourea in di-xylenyl (mixed) ditliiophosphoric acid. E10% solution of di-o-tolyl thiourea in di-xylenyl (mixed) dithiophosphoric acid.

TABLE II SCREEN ANALYSES or GROUND PULPS Per cent weight retained Mesh size 5 in. grind ore No. 2

FLO'I'A'I'ION 'Onn No. 1

A ground charge of the orewas transferred to a laboratory-size Fagergren flotation machine and diluted to approximately 22% solids with laboratory tap water. In tests 1 and 2 where thiocarbanilide alone and di-o-tolyl thiourea alone were tested, 0.112 lb./ton-of cresylic acid and from these it will be seen that the recoveries 1 of silver and lead with the 6% solution of di-tolyl thiourea in di-xylenyl (mixed) dithiophosphoric acid are 76.37 and 80.51% respectively as compared to 76.31 and 81.03% using a 6% solution of di-phenyl thiourea. These results show that the g 6% solution of the di-tolyl thiourea is at least the equivalent of a 6% solution .of the di-phenyl thiourea; whereas the di-phenyl thiourea alone of test No. 1 is far superior to those of test No. 2

using di-tolyl thiourea alone. In test No. 5 using a a 10% solution of di-tolyl thiourea in di-xylenyl (mixed) dithiophosphoric acid, the results are far superior to those of any oi the other tests. I

Per cent dist. I

The re- Cresylic acid Per cent dist.

Promoter (variable) Pb, per cent Tailing Assay oz./ton

.Tailing Assay.

oz./ton

Per cent wt.

at mum NazCOa Reagents, lbs/ton Per cent Pbv - ZnSOt NaCN Per cent dist.

' Per cent dist.

TABLE IV Per centin equal quantities. The results of test No. 3 show that the use of a 10% solution of di-tolyl 5 thiourea produces results which are greatly superior to the use of the 6% solution of'diphenyl thiourea. v

Another series of tests were conducted on ore sample No; 2 and the procedure was essentially the same as that described' heretofore. sults of these tests are reported on Table No. V.

Pb, per cent Test results Concentrate Assay s. oz./ton

Tasrs on Our: No. 2 Test conditions mm m a U mm PW m m C m u m i w 0 L e R z L I N 0 w N 4 m a TB em 623 mm fim .1 I L L I 1 I n I o I m I m z 0 t. I .m m m "m I L mfia nmm GCF TABLE V Test conditions.

solids Test results Concentrate Assay oz./ton

4 Per cent.

Per cent Per cent Feed :wsay

oz./ton

Feed assay oz./ton

Promoter (variable) Point of addition Promoter (variable) Test N0.

F-6% solution of di-phenyl tliiourea in di-xyleny] (mixed) dithiophosphoric acid. (Ii-6% solution of di-o-tolyl thiourea in di-xylenyl (mixed) dithiophosphorlc aeid.f H 10% solution of di-o-tolyl thiourea in di-xylenyl (mixed) dithiophosphoric acid.-

An analysis of the data 'of Table IV shows that the recoveries of silver and lead using a 6% solution of di-o-tolyl thiourea in di-xylenyl 3 (mixed) dithiophosphoric acid were 66.25 and 90.33% respectively, as compared to recoveries of 64.70 and 90.00% using a 6% solution of di-phenyl thiourea in di-xylenyl (mixed) dithiophosphoric acid, indicating that the di-tolyl 40 thiourea solution is a more effective promoter than the di-phenyl thioureasolution when used 'Grinq.

Test No.

I6% solution of di-phenyl thiourea in di-xylenyl (mixed) dithiophosphoric acid. J6% solution of dj-phenyl-thiourea in di-xylenyl (mixed) dithiophosphoric acid. K-10% solution of di-o-tolyl thiourea in di-xylenyl (mixed) dithiopl osphoric acid.

Lr-6% solution of di-(mlxed) xylyl thiourea in di-xylenyl(mixed) dithiophosphoric acid.

. M10% solution of di-(mixed) xylyl thiourea in di-xylenyl (mixed) dithiophosphoric acid.

An analysis of the data in Table V shows that tests Nos. 3, 4, and using solutions of ditolyl thiourea or di-xylyl thiourea in di-mrlenyl those of comparative tests Nos. 1 and 2 using solutions of di-phenyl thiourea in di-xylenyl (mixed) phosphoric acid.

A series of comparative tests were also con- The metallurgical results on metallic copper in the above table show that the use of a solution of di-o-tolyl thiourea in'di-xylenyl (mixed) dithiophosphoric acid improved both the recovery and concentrate grade over the test using a solution of di-phenyl thiourea. in di-xylenyl (mixed) dithiophosphoric acid.

While in the above description and examples the application of the invention has been described in conjunction with a lead-silver ore,

the invention is not limited to these ores as this improved reagent combination is also superior in its results on zinc, copper, gold, as well as other base or other precious metal ores. The substituted di-aryl thioureas may be used in conjunction with other dithiophosphoric acid compounds, as for example, a solution maybe made of the substituted di-aryl thioure'a with the ammonium salt of di -amyl dithiophosphoric acid. In somecases the mixture of the di-substituted di-aryl thlourea and di-organic dithiophosphoric acid does not remain liquid at ordinary temperatures, and it is usually preferable to add to the solution a suitable diluent such as water, ethyl alcohol, or the like which renders the composition fluid at ordinary temperatures.

It is to be noted that the present invention relates to the use, of a reagent combination comprising a solution containing a minor proportion of substituteddi-aryl thioureas, such as dio-tolyl thiourea and di-xylyl (mixed) thiourea and a major proportion of an organic dithiophosphoric acid compound. In the composition of the present invention it is shown that di-tolyl thiourea. or di-xylyl thiourea is soluble to the extent of about in di-xylenyl (mixed) dithiophosphoric acid and that such a composition is a more effective promoter than similar compositions used heretofore.

From the above it will be apparent that there ganic dithiophosphoric acid compound and from 6 to 10% gf di-tolyl thiourea.

2. A composition of matter comprising an organic dithiophosphoric acid compound and from 6 to 10% of di-xylyl thiourea. v

3. A composition of matter comprising dixylenyl dithiophosphoric acid and from 6 to 10% of di-tolyl thiourea.

4. A composition of matter comprising dixylenyl (mixed) dithiophosphoric acid and from 6 to 10% of di-xylyl thiourea. a

5. A method of flotation of metal ore values which comprises providing a pulp of ore and water, adding thereto a flotation promoter including a mixture of an organic dithiophosphoric acid compound and from 6 to 10% di-tolyl thiourea. and subjecting the pulp to a froth flotation operation.

6. A method of flotation of metal ore values which comprises providing a, pulp of ore and water, adding thereto a flotation promoter including a mixture of an organic dithiophosphoric acid compound and from 6 to 10% di-xylyl thiourea. and subjecting the pulp to a froth flotation operation.

7. A method of flotation of metal ore values which comprises providing a pulp of ore and water, adding thereto a flotation promoter including a mixture of di-xylenyl dithiophosphoric acid and from 6 to 10% di-tolyl thiourea., and subjecting the pulp to a froth flotation operation.

8. A method offlotation of metal ore values which comprises providing a pulp of ore and.

water, adding thereto a flotation promoter including a mixture of di-Xylenyl (mixed) dithiophosphoric acid and from 6 to 10% of di-xylyl thiourea and subjecting the pulp to a froth flotation operation.

9. A composition of matter comprising an organic dithiophosphoric acid having dissolved therein from 6% to 10% of an alkyl substituted diphenyl thiourea.

10. A composition of matter comprising an aryl dithiophosphoric acid having dissolved therein from 6% to 10% of an alkyl substituted diphenyl thiourea.

11. A composition of matter comprising an or-. ganic dithiophosphoric acid having dissolved therein from 6% to 10% of ditolyl thiourea, and a diluent.

12. A composition of matter comprising an organic dithiophosphoric acid having dissolved therein from 6% to 10% of di-xylyl thiourea., and a diluent.

13. A froth flotation method for recovery of metal ore values which comprises subjecting an orc containing recoverable metal ore values to a froth flotation treatment in the presence of a promoter comprising an organic dithiophosphoric acid having dissolved therein from 6% to 10% of an alkyl substituted diphenyl thiourea.

14. A froth flotation method for recovery of metal or; values which comprises subjecting an v CERTIFICATE OF CORRECTION. Patent No. 2,550,587 September 28, 19b3, DAVID WALKER JAYNE, JR.

It is hereby certified that error appears in the printed specification of theabove numbered patent requiring correction as follows: Page 1.1., first column, line Lt, before the wor'd "those" insert --(mixed dithiophosphoric acid are better than--; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 16th day of November, A. D. l9lt5.

Henry Van Arsdale, (Seal) I Acting Commissioner of Patents. 

